Is it possible to weld/repair this cast Iron machine part?

FrankFalcon

Hi all

Before I start please allow me to say I Don’t mind paying for a service if what I want can be achieved. 

My brother works at a small factory that has some very old manufacturing machines. From time to time some of the components or parts on the machines do break and because of the very old age of the machines the parts are not available anymore. One such part is shown the photographs here. This item is part of a very old stair manufacturing press. It looks like it is made of cast iron. My first option was to phone my friend who is a welder (and makes things like gates). I showed him the photos and he said if it is cast it is not something I can weld but it could be an alloy. He also told me that there may be specialist companies out there who can weld this item but he said unfortunately it is out of his sphere. I think he might have mentioned Tig welding???

With this in mind, are there any welding experts on here who can give me advice on if this part can be repaired? I am not sure when, but by the look of it this item looks like it has possibly been welded once previously which leads me to believe that we might be in luck getting this welded repaired again. 

Thanks all 

bryanb

It is possible given the right welder, also the right equipment etc

FreeBear

Have done welding and machine repairs in the past....

Yes, it is possible to weld cast iron - It needs preheating in an oven before welding with the appropriate rods. Then it needs to be put back in the oven to cool down very slowly. Once cool, the welds can be dressed & cleaned up. However, the weld will always be a weak point and likely fail again.

It looks to be a relatively simple part with a pneumatic cylinder inside - It might be as cheap to get a replacement fabricated in mild steel. Less likely to break again, and easier to repair if it does.

daveyjp

Have a look at Doubleboost on youtube and drop him an email.

FrankFalcon

Thank you all. 

Section62

He hasn't posted on this forum for a long while, but @snowcat75 is an exceptionally talented welder and might be able to advise.

He's still around posting on another forum, so you might be able to find him there.

I'm no expert, but I wouldn't be surprised if the part isn't standard cast iron but is something malleable instead - CI is not good in tension and the impression I get looking at that part is it may be subject to tensile forces in normal use.  If it is CI and is subject to tensile forces then it may mean shelling out for a replacement in a more suitable material makes more sense.

ThisIsWeird

Hi FrankF.

Can cast iron be welded? Yes - a part on my dad's old Hattersley Loom was welded successfully when it snapped clean through, and that was 55 years ago.

Your bottom component looks a far more complicated job, tho', as there's a lot of depth to the break which cannot be filled with weld. So I wonder if an alternative - I presume the two parts fit together snugly? - would be to resin them together, and make a steel strap to go around the whole part to hold it firm - 5mm thick or even more? I guess it depends on the forces it'll have to take.

The other repair seems more tackleable. I think these are done by grinding a large V along the outside, as deep as the crack, and this is back-filled with built-up layers of weld. I wouldn't be surprised if that piece could be tackled with relatively little issue. But I don't know...

nofoollikeold

1. Cast iron can be welded, but needs someone with really good experience and the right equipment.  
2. Many people prefer to repair by brazing / silver soldering.  
3. It looks to me as if the casting has already been repaired at least once.  All trace of that repair would have to be removed, which might leave gaps to be bridged.  
4. Unless the piece is made of cast iron because it slides against another part, I think suggestions above of repairing (reinforcing) or replacing with a fabricated mild steel piece would probably prove the most durable.
5. A way out, lengthy and probably costly alternative would be to measure, make a pattern (3D printed?), and have another casting made and machined.  You'd probably have to leave the casting for 12 months after manufacture to let the stresses work out, otherwise it could warp on machining.